1. Field of the Invention
The present invention relates to an image capture technology that comprises an optical viewfinder mode, which employs an optical finder to observe a subject of an image, and an electronic viewfinder mode, which employs a display unit to observe the subject of the image.
2. Description of the Related Art
A conventional image capture apparatus comprises an optical viewfinder mode, which employs an optical viewfinder to observe a subject of an image, and an electronic viewfinder mode, which employs a display unit to observe the subject of the image. The electronic viewfinder mode retracts a first shutter blade from a light path of an image capture element, and captures an image of a subject upon the image capture element. In such a circumstance, a yoke adhesion surface of a magnet for controlling the first shutter blade is in an exposed state until after a photograph is taken, whereupon it is transitioned to an original position. Accordingly, when a photographer takes time to decide upon a composition, an amount of time wherein the yoke adhesion surface of the magnet for controlling the first shutter blade is in the exposed state increases. As a result, a problem arises wherein a timing precision of the shutter may deteriorate, and may become incapable of properly maintaining an armature, owing to dirt, dust, or other debris infiltrating the yoke adhesion surface of the magnet for controlling the first shutter blade, and consequently impeding the adhesion of the first shutter blade.
In response thereto, Japanese Patent Laid Open No. 11-041523 discloses a technology wherein the shutter unit comprises only a rear shutter blade as a shutter blade unit, and that controls an exposure time of an image capture element that uses an X-Y address scheme by aligning a commencement of an accumulation of an electric charge of the image capture element with a travel characteristic of the rear shutter blade. The technology disclosed in Japanese Patent Laid Open No. 11-041523 does not, however, take into consideration a change in the travel characteristic of the shutter blade unit, which may arise as a result of, for example, a change in an attitude of the camera, or a temperature of an environment wherein the camera is being used. As a consequence, a lack of uniformity of the exposure time, under such a circumstance as when a fast shutter speed is set, will have an increasingly significant effect. The lack of uniformity of the exposure time will also have an increasingly significant effect when an effect of such as the temperature of the environment wherein the camera is being used with regard to a reset operation of the image capture element and the rear shutter blade varies significantly, when controlling the commencement of the exposure via the reset operation of the image capture element.
In response thereto, Japanese Patent Laid Open No. 2001-235779 discloses a technology wherein a photo refractor is employed to detect a difference in a travel characteristic of a first shutter blade as the shutter blade unit and the travel characteristic of a rear shutter blade as the shutter blade unit, and a result of the detection thereof is taken into account in a following driving of the shutter blade unit.
A configuration that is disclosed in Japanese Patent Laid Open No. 2001-235779 is capable, however, of detecting the travel characteristic of the shutter blade unit only when the rear shutter blade as the shutter blade unit is actually being made to travel. As a consequence, the result of the detection thereof would be taken into account in a photograph after the following photograph. Accordingly, a problem arises whereby no guarantee exists that a photograph that is taken subsequent to the detection of the travel characteristic of the shutter blade unit will be taken under a condition that is identical to a condition that applies when the travel characteristic of the shutter blade unit is detected, owing to a plurality of such various factors as the attitude of the camera, the temperature or a humidity of the environment wherein the camera is being used, a state of a power supply, a number of operations that have been performed, or an interval between one photograph being taken and a following photograph being taken.